Ph probes OFF

[2 TAZ]

I have 2 PH probes, both > 1yr old.

About 1 month ago I placed both probes in sump and the varied by .2 so I re-calibrated both probes, all looked good. I left both in sump, after a week or so 1 instantly rose .2 I figured the probe may be going bad. I re-calibrated both probes, both read true. Placed the probe that jumped in calcium reactor and ordered new probe. About 2 weeks pass. Ready to change bad probe. Took probe out of calcium reactor and placed in sump, now probes are off by .5 Placed in 7.0 solution. Probe in reactor that previously rose by .2 is about .2 higher. Other probe is showing more then .2 lower
In sump 1 reads 8.26, the other 7.75

Do I have 2 bad probes???
I had a ORP probe go bad recently, it was reading #s way out of range. Do the Ph probes go bad like this?
What should I do?? I know the probes are over 1 yr. old but I don't want to have to buy 2 new probes if I don't need to.
I tried cleaning with viniger and toothbrush--no change

Anyone else having these problems?

Thanks for any input.

I would try calling Neptune but Curt has not been too helpful with other problems I have.

 

[Deleted member 143833]

Generally if a probe calibrates correct and then reads correctly in the solution after calibration is would be a good indication the probe is good. That said; what you describe after the probes are placed in water sounds suspiciously like you may have some current leakage from something in the water that is affecting the reading. You didn't mention the controller you are using; the AC3 family is more sensative to stray current than the Apex so if you can try moving the probes to a different location and see if they respond differently. You also didn't mention the probe type; standard or lab grade. Another thing to consider is how long it takes to settle during calibration; if you get much more than 1-2 minutes then the probes are old and should be replaced; be sure to give sufficient time to settle; not enough can cause what you see also.

Just a few things to try...

 

[2 TAZ]

Thanks, Kenargo
I re-calibrated the 2 questionable probes last night as well as the new one. All probes are standard grade and re-calibrated without any issues. I am using an Apex but moved 1 of the old probes to an ACIII. All probes are looking good so far. I did notice something in the graph when I was tracing the history back to see if I could see when the probes went out of calibration. There was a much longer then usual time period between graph points about a week back. I'm guessing this is when they came out of calibration. I'm not sure why this happened though.

 

[2 TAZ]

1 of my probes instantly jumped again last night, this time by 0.07 and is now reading 0.10 above the other probes. All three probes are within inches from each other. This is getting frustrating!

 

[swearint]

There was a much longer then usual time period between graph points about a week back. I'm guessing this is when they came out of calibration. I'm not sure why this happened though.

This indicates a lack of data. I have seen this sometimes when the Apex reboots and the data files get corrupted. The Apex indicates at the bottom of the Status Page when the last Power Failed occurred.

Todd

 

[2 TAZ]

Until yesterday the probes have remained stable at a 0.10 difference. Then the new probe jumped from 8.12 to 7.73, then up to 7.98 then down to 7.74 then 7.88 while the other 2 probes remained stable at about 8.24. All this transpired within 1 hour while no additions to the tank were made. I placed the three probes together in a 7.0 solution and the new probe read 6.67. The new probe is connected to the Apex, the other to a px1000, temp comp. is on and the temp has remained stable.

 

[2 TAZ]

Now they read 8.21 and the new probe is all the way down to 7.37

 

[2 TAZ]

Now the probe is down to 6.92

 

[Hawkdl2]

A properly functioning pH probe should not produce such erratic readouts. In addition, a failing probe "usually" will manifest as slow-to-respond before they begin reading erratically. You can test this by monitoring how long it takes the probe to settle when calibrating between pH 4, 7 or 10. If the probes calibrate fairly quickly (less than 30 seconds) and are clean, the problem is not the probe. I don't know how sensitive they are to interference, but have you checked to see if the probe is collecting air bubbles where it's located? Is there excessive debris in the water around the probe? Close to a Ca Rx outlet? Low oxygen/low flow portion of your refugium? All of these things could cause localized pH fluctuations or low pH in the test area. Try putting the probe in the main tank.

 

[Meitzler]

Ph Probe Varing

Ph Probe Varing

I am experiencing a similar problem. I have a total of 4 ph probes, 2 each on APEX controllers but all in the same tank. Each of them calibrate right on the money at 7.0 and 10.0. But like you noted within a day, they vary considerably. Initially, they are within .05 of each others when placed in the tank water. A day later, the maximum variance at any point in time is .15. I was hoping they would stay within .05 of each other, but have not been able to achieve this. Suggestions!

 

[2 TAZ]

Hawkd12: All probes are clean in high flow sump, without air bubles, no ca. reactor. Calibrate quick, and the new probe is now the off probe (the one plugged directly into the Apex). The Ph is not fluctuating in the tank, only the probes reading of it. It keeps dropping too.
Now it is down to 2.0 lower then accurate (other probes)

Meitzler: I have contacted Curt at Neptune with this problem as well. Everything He suggested has not helped, but heres what he said: He believes it is external interference. If this is true it only seems to badly be affecting 1 of my ph probes, the one I have in the Apex. It took a while for my probes to go off by so much, try leaving you're probes without re-calibrating to see if this happens to you(unless of course it is controlling something like a ca or kalk reactor)

Heres what I tried:
I re-calibrated multiple times
Switched probe postions(where the probes plug into)
Installed new probe
tried unplugging temp probes
tried seperating probe in a seperate container to make sure no grounding issues

None of the above helped at all
The probe that strays the most has alwasy been plugged directly into the Apex PH port. The other 2 probes varry be about 0.10, which maybe is normal for a standard probe.

I had sent the Apex back to neptune a little over a month ago for othe reasons. Curt checked it out and said all was well. However this probe problem dose not manifest itself right away, and at the time I did not know about this problem so he was not specifically looking for this problem. He has recently said he very strongley doubts anything is wrong with it though as he just check it out.

Please let me know how you make out it sounds like you may have the same problem. I will let you know if I can get the problem fixed. If possable, could you send Curt an e-mail, maybee he will take this problem more seriously if he sees more peolpe then just us are affected.

I am leaving for Florida for 2 1/2 weeks this Friday. I am planning on re-calibrating and switching probe possitions again before I leave.

 

[Hawkdl2]

Since these are not high end probes (I pay a LOT more for high end pH probes in my lab), it is very possible that the variable calibration drift you see is inherent in the probes themselves. Most of us do not have multiple probes in the same place to compare, so we would never know how "off" the pH readings are that we see. To test this, try calibrating the probe connected directly to the Apex base unit using pH 7 and 10 solutions, then leave the probe in the pH 7 solution for a day - or whatever period you think typically results in calibration drift. You might wrap the top of the calibration solution with Saran wrap to minimize evaporation and pH shift of the solution. Make sure the cable does not cross over and run adjacent to any other probe or electrical wire (if possible) to try an rule out interference. In any case, the idea is to use a solution with a stable pH - not the water in your tank. However, if you don't have a bottle of pH7 solution, you can make an similar solution if you search the Chemistry forum for a recipe. you might also just use a sample of NSW in a separate bottle.